7.05 Photosynthesis and Cellular Respiration: Complimentary Processes

Plants don't need a kitchen. They can make food for themselves.

Imagine you're walking in the garden pictured on the right. Take a deep breath. Now let it out. What you just inhaled was a mixture of gases, but your body takes in the oxygen. What is exhaled is mainly carbon dioxide gas. Humans inhale oxygen and exhale carbon dioxide. The carbon in the carbon dioxide gas you just exhaled is the same carbon that plants use to make food and store energy.

Let's review the general chemical equation for photosynthesis and cellular respiration. As you examine each, look carefully for relationships between the two.

Text-only version

Remember that all cells (plant cells too), must produce energy that their cells can use to take care of cellular business; most of the time this happens through the process of cellular respiration.

• In cellular respiration, cells use the oxygen and food produced by plants.
• Then in photosynthesis the plants use the carbon dioxide produced through respiration.

Do you see that this is the ultimate in recycling? Do you also see why understanding these two processes and figuring out ways to keep them in balance within an environment like the BioDome is exceedingly important?

Let's Dig Deeper

Grab your Travel Log. It is time to do a little research on the process of photosynthesis.

• Copy and paste the questions below into a Notes Page in the left column.

• Work through the information in the web Resource to answer the questions.

• Place your Notes Page in your Travel Log.

1. In the cycle part of the program: click on the kid, water can, and the window. After the molecules begin to exchange between the kid and the plant, what happens as you close the window?

2. How are the kid and the plant using each other?

3. In the atomic shuffle, what does the energy from the sun do to the hydrogen in each water molecule (H₂O)?

4. Where does the oxygen gas (O₂) come from?

5. In what part of the plant does photosynthesis take place?

6. How does carbon dioxide (CO₂) get inside the plant?

7. We know plants need carbon dioxide (CO₂) to live and make food, but why do plants need oxygen to survive? (Hint: Check out the "Three Puzzlers.")

Web Resource: Illuminating Photosynthesis

When you have completed this activity move on to the Travel Log tab.